#![feature(plugin)] #![plugin(clippy)] #![allow(unused_variables)] fn takes_an_immutable_reference(a: &i32) { } fn takes_a_mutable_reference(a: &mut i32) { } struct MyStruct; impl MyStruct { fn takes_an_immutable_reference(&self, a: &i32) { } fn takes_a_mutable_reference(&self, a: &mut i32) { } } #[deny(unnecessary_mut_passed)] fn main() { // Functions takes_an_immutable_reference(&mut 42); //~ERROR The function/method "takes_an_immutable_reference" doesn't need a mutable reference // Methods let my_struct = MyStruct; my_struct.takes_an_immutable_reference(&mut 42); //~ERROR The function/method "takes_an_immutable_reference" doesn't need a mutable reference // No error // Functions takes_an_immutable_reference(&42); takes_a_mutable_reference(&mut 42); let a = &mut 42; takes_an_immutable_reference(a); // Methods my_struct.takes_an_immutable_reference(&42); my_struct.takes_a_mutable_reference(&mut 42); my_struct.takes_an_immutable_reference(a); }